Cellular article

ABSTRACT

An article including generally parallel, elongated members at least some of which have bulbous portions along the lengths thereof which are bonded to adjacent of such members so that the members together provide an integral article. The elongated members are formed of polymeric material, the molecules of which are oriented at least along one of the longitudinal and transverse directions of the article.

United States Patent 167, 117. 321,47,s4, 291,2ss-290; 161/122.127,139,178,179,159,402;260/2.5;181/33; 156/296, 77, 7a, 244. 500

[56] References Cited UNITED STATES PATENTS 2,171,805 9/1939 Picard5/361 2,772,193 11/1956 Ono 16l/DIG.6 3,015,873 1/1962 Dietzschetal.l6l/l78X 3,226,285 12/1965 lovenko 161/72 3,344,221 9/1967 Moody et a1260/25 X FOREIGN PATENTS 861,447 2/1961 Great Britain 161/127 PrimaryExaminer-William A. Powell Attorneys-Thomas R. OMalley, George F.Mueller and Eugene G. Horsky ABSTRACT: An article including generallyparallel, elongated members at least some of which have bulbous portionsalong the lengths thereof which are bonded to adjacent of such membersso that the members together provide an integral article. The elongatedmembers are formed of polymeric material, the molecules ofwhich areoriented at least along one of the longitudinal and transversedirections of the article.

PATENTEU SEP21 [911 CELLULAR ARTICLE 1 he present invention relates toan improved article of manufacture, preferably having a cellularstructure.

A primary object of the present invention is to provide a generally newor improved and more satisfactory article of cellular structure.

Another object is the provision of an improved article having a cellularstructure and which is formed of polymeric material, the molecules ofwhich are oriented.

Still another object is to provide an improved molecularly orientedfoamed article of manufacture which is decorative in appearance and ofnetlike construction.

A still further object is the provision of a thick and generally rigidarticle having a network of passages extending therethrough.

These and other objects are accomplished in accordance with the presentinvention by an article which includes a plurality of generallyparallel, elongated members which are bonded to members adjacent theretothrough bulbous portions which are formed along the lengths of at leastcertain of such members whereby the plurality of elongated memberstogether provide an integral article.

In the preferred construction, the bulbous portions are preferably ofcellular structure, similar in shape, size and in the spacing thereofalong the lengths of the respective elongated members and may be eitheraligned generally transversely of a plane extending longitudinally ofsuch members or in staggered relationship. In a construction havingaligned bulbous portions, the bulbous portions of adjacent of suchmembers are bonded to each other and are separated by continuous,straight openings which extend completely through the resulting article.Alternatively, in a construction having staggered bulbous portions thebulbous portions of each of the members are bonded to adjacent membersbetween bulbous portions thereof. in this latter arrangement, thestaggered relationship of the bonded bulbous portions may providearticles which are of generally continuous and unbroken construction orwhich have openings therein.

The articles of the present invention may consist of a single layer orrow of elongated members bonded to each other in side-by-siderelationship or a plurality of layers in which the elongated members inat least some of the layers are bonded to each other in side-by-siderelationship or are spaced from each other and bonded to elongatedmembers in adjacent layers. The bulbous portions may vary in size, shapeor spacing along the individual elongated members.

Articles of the present invention which are perhaps simplest in formconsist of elongated members bonded to each other in side-by-siderelationship, with each of such members having bulbous portions whichare similar in size, shape and spacing. in such article, thelongitudinally spaced bulbous portions of adjacent elongated members maybe aligned with and bonded to each other.

A single layer of elongated members having aligned and bonded bulbousportions provides a netlike article which has good flexibility in bothits longitudinal and transverse direction and is useful, for example, asa cushioning material. if such article is formed of a polymericmaterial, it may be uniaxially or biaxially stretched to orient themolecules thereof and render such article suitable for uses, such as anonwoven fabric, rug backing or in laminated or composite structures.

Articles formed of a number of layers of such elongated members, inwhich the aligned bulbous portions are bonded to each other, are morerigid and can be rather massive in size, if so desired. Generally,straight openings extend through such article from all sides, giving ita honeycomb structure. Articles of this character are relatively strong,yet light in weight and are useful, for instance, in space-filling orshock-insulating applicationsv in articles of the present invention, theelongated members may also be bonded together in a sideby-sidearrangement, with the bulbous portions, which are similar in size, shapeand spacing, of adjacent elongated members being in staggered or ofi'setrelationship. if such bulbous portions are spaced along their respectivemembers a distance less than the length of an individual bulbousportion. generally no openings exist between adjacent bulbous portionsin the resulting article. On the other hand, if the spacing of suchbulbous portions exceeds their individual lengths, the resulting articleis netlike in appearance or includes tortuous passages extendingtherethrough, depending upon the number of layers of the elongatedmembers bonded together.

While preferred, the bulbous portions of the elongated members need notbe of the same size, shape and spacing. It is essential, of course, thatall of the elongated members forming an article be bonded to each other.Thus, the bulbous portions of adjacent elongated members of an articlemay be of such size, shape or spacing that they are bonded to each otherat certain locations, yet at other locations the bulbous portions ofsuch members may be bonded to the adjacent member between its bulbousportions. It is also possible to provide articles in which adjacentelongated members in the same plane are not directly bonded to eachother but are bonded to elongated members in adjacent planes whichthemselves are bonded to each other.

From the standpoint of ease of manufacture, the bulbous portions of theelongated members are preferably of spherical or perhaps ellipticalconfiguration. Preferably, at least the bulbous portions of theelongated members are of cellular construction, with each containing atleast one and desirably a multiplicity of voids. If desired theelongated members and/or the bulbous portions thereof may be differentin color and/or at least some of the bulbous portions may containreflective material, such as aluminum particles or flakes to impartdecorative effects of the resulting articles.

Preferably the articles of the present invention are formed of polymericmaterials which are customarily employed in the manufacture of foamedarticles. Such polymeric materials include the normally solid polymersor mixtures of polymers, including such materials as polymers ofethylene, propylene, styrene, vinyl chlorides, etc., as well asmaterials of cellulosic polymers and derivatives thereof, as forexample, in the form of viscose and cellulose acetate solutions.

in general, the method employed in making the articles of the presentinvention includes the steps of extruding a plurality of continuous andgenerally parallel streams of flowable strand-forming material, causingat least some of the extruded streams to periodically expand while thestrand-forming material thereof is in a flowable condition to providebulbous portions at spaced intervals along the lengths thereof whichcontact and bond with streams adjacent thereto during the expansionthereof, and setting the extruded strand-forming material to solidifythe streams into an integral structure.

The periodic expansion of the streams of strand-forming material may beeffected by intermittently injecting a fluid into such streamsconcomitantly with the extrusion thereof. The injected fluid may assistin setting of the streams and may be either a liquid or a gas or amixture thereof. Alternatively, the bulbous portions may be formed alongthe lengths of the extruded streams of strand-forming material, whichmay be either a froth or homogeneous material, for example, byperiodically varying the extrusion pressure and/or the rate at which theresulting elongated members or resulting article is taken up orcollected. Foamable compositions include, for example, a thermoplasticpolymeric material containing a chemical blowing agent which isdecomposed and causes the strand-forming material to foam as it isextruded into a zone of lower pressure.

The degree of periodic expansion of the stream of strandforming materialis such as to provide bulbous portions along the length thereof whichcontact and bond with the strands which are adjacent thereto. Theextruded streams may be periodically expanded simultaneously, wherebythe bulbous portions of adjacent streams contact and bond with eachother along planes extending generally perpendicular to the direction ofextrusion, The article formed by this procedure,

as heretofore mentioned, will have a netlike structure with openingsbeing formed in the article between adjacent bulbous portions.Alternatively, the periodic expansion of adjacent extruded streams maybe effected in out-of-phase relationship, so that the bulbous portionsof each stream are staggered with relation to the bulbous portions ofstreams which are adjacent thereto.

It will, of course, be apparent that the periodic expansion of theindividual extruded streams may be varied as to degree and/or frequencyand may differ from the periodic expansion of streams which are adjacentthereto. Further, the rate at which expansion occurs to provide anindividual bulbous portion may itself be varied to provide such bulbousportion with a desired shape.

In the drawing,

FIG. I is a diagrammatic view illustrating one mode of practicing themethod employed in making articles of the present invention;

FIG. 2 is a section through an article of the present invention takenalong the line II-II of FIG. 1;

FIG. 3 is a section similar to FIG 2 taken through another article ofthe present invention;

FIG. 4 is a view similar to FIG. 1 showing another mode of practicingthe method employed in making articles of the present invention;

FIG. 5 is a section through an article as produced by the method shownin FIG. 4',

FIG. 6 is a view similar to FIG. 1 showing a further mode of practicingthe method employed in making articles of the present invention;

FIG. 7 is a view similar to FIG. 1 showing a still further mode ofpracticing the method employed in making articles of the presentinvention; and

FIG. 8 is a section through a composite product showing one use of anarticle of the present invention.

With reference to the drawing, FIG. I illustrates an extrusion device 11having a cavity I3 into which a flowable strandforming material 15, asfor example a molten, thermoplastic polymeric material, is deliveredunder pressure through a pipe 17 from a suitable source, not shown. Arow of openings 19 extend through wall 21 of the extrusion device 11 fordischarging the strand-forming material as a plurality of spaced,continuous streams 23. Fluid injection capillary tubes 25 project from asupply header 27 and have conical or tapered free ends which are alignedwith and extend into the extrusion openings 19.

In the operation of the above-described apparatus the flowablestrand-forming material 15 is extruded under pressure from the cavityand through the openings 19 as continuous streams 23. A fluid,preferably air, is delivered under a pulsating pressure from a suitablesource, not shown, through the header 27 and tubes 25 and is injectedsimultaneously into all of the streams 23. This injected fluid serves toperiodically expand the extruded streams of strand-forming material 23into bulbous portions 29 each having void 31.

The degree of periodic expansion of the streams of strandformingmaterial 23 is such that the bulbous portions 29 which are formed alongadjacent of such streams contact and bond with each other. After suchbulbous portions have bonded, the strand-forming material is set, as byone or more streams of cool air supplied by suitable nozzles, not shown.

The article 33 formed by the above-described method includes a series ofelongated members 35 which are connected to each other at the locationsof contact of the bulbous por tions 29. Openings 37 extend through thearticle between the locations at which the bulbous portions are bondedto each other, thus giving the article 33 a netlike construction. Thearticle 33 may be stretched along one or both of its axial directions,using conventional equipment, to orient the molecules thereof and thusimprove its strength properties.

As shown in FIG. 2, the article 33 formed by the abovedescribed methodconsists of a single layer or elongated member 35 connected to eachother in side-by-side relationship. The extrusion device 11 may beprovided with additional rows of extrusion openings 19 and capillarytubes to provide multilayered articles 39, as shown in FIG. 3.Substantially straight and intersecting openings 41 extend through thearticle 39 from all of its sides giving it a generally honeycombconstruction.

The method illustrated in FIG. 4 employs an apparatus similar to that ofFIG. I, with the exception that adjacent tubes 25 are connected toseparate fluid supply means, not shown. This may be achieved, forexample, by having alternate tubes 25 connected to the same fluid supplyheader or by having a separate fluid supply means for each tube 25.

In practicing the method with the apparatus of FIG. 4, continuousstreams 23 of strand-forming material extruded from the openings 19 areperiodically expanded into cellular bulbous portions 29 by fluidinjected into such streams by the capillary tubes 25. The fluidinjection into the extruded streams 23 by alternate tubes 25 occurssimultaneously and alternately with the injection of fluid by the tubes25 which are directly adjacent thereto. In this manner, the bulbousportions 29 along adjacent extruded streams 23 are in staggeredrelationship. The degree of expansion of the streams of strandformingmaterial is such as to have the bulbous portions 29 of each stream atleast contact with the streams adjacent thereto.

The article 43 produced by the method shown in FIG. 4 consists ofasingle layer of elongated members 45 having bul bous portions and astaggered array of openings 47. Stretching of the article 43 to inducemolecular orientation may be effected by conventional equipment. As withthe method shown in FIG. I, the method illustrated in FIG. 4 may be usedto make multilayer articles 49 as shown in FIG. 5. The article 49includes openings 51 which extend from all sides thereof and whichtogether follow tortuous paths through the article itself.

A method particularly adapted for use in making articles form foamablestrand-forming compositions, as illustrated in FIG. 6. The foamablecompositions may include, for example, a thermoplastic polymericmaterial, such as polypropylene, and a chemical blowing agent, as forexample azodicarbonamide, which decomposes as the thermoplastic materialis rendered molten and provides a saturated solution of gases within themelt at the particular extrusion temperature and pressure conditionswhich are to be employed. Various additives, such as blowing agentactivators, nucleating agents, pigments, etc. may also be incorporatedinto the foamable composition.

As shown in FIG. 6 a foamable composition 53, as described above, isdelivered under pressure from a suitable source, not shown, to anextrusion device 55 by a conduit 56. A row of openings 57 extendsthrough wall 59 of the device 53 from which the foamable strand-formingmaterial issues as a series of continuous streams 61. As such streamsleave the openings 57 and enter into the surrounding atmosphere, whichis under lower pressure, the gases contained therein cause the same toexpand.

Periodically, the extruded streams 61 of strand-forming material aretensioned and thus stretched as they leave the openings 57 of theextrusion device 55. Such tensioning of the streams may be effected, forexample, by a pair of nip rolls 63 and 65 which are driven at a varyingrate of speed and engage with the extruded material which has been set.The sections of the extruded streams 61 of strand-forming material whichare so tensioned and stretched will thus expand to a lesser degree thanthe sections which are adjacent thereto. These latter sections will thusappear as bulbous portions, as indicated at 67.

The degree to which the individual streams are permitted to expand mustbe such as to permit the bulbous portions 67 of adjacent streams tocontact and bond with each other. Quenching of the contacting streams offoamed material may be achieved, as by streams of cool air.

Foamable strand-forming material may also be extruded into articles in amanner as shown in FIG. 7. The apparatus employed includes an extrusiondevice 69 into which a foamable composition 71 is delivered underpressure. Openings 73 extend through wall 75 of the device 69 andneedles 77 project into such openings. Suitable means, not shown, areprovided for reciprocating alternate needles 77 simultaneously and inalternate sequence with the needles 77 adjacent thereto.

In operation, foamable strand-forming material issues from the openings73 of the extrusion device 69 as continuous streams 79. Each of thesestreams will expand as they enter into the surrounding atmosphere andwill contact and bond with the streams which are adjacent thereto.Periodically the flow of foamable strand-forming material passing intoand through the openings 73 is partially closed off by the needles 77,with such restricted flow occurring simultaneously through alternateopenings 73 and in alternate relationship with the openings 73 adjacentthereto. Thus, each of the streams of strand-forming material issuingfrom the openings 73 are each formed with bulbous portions 79, with thebulbous portions of adjacent streams being in staggered relationship.

During the expansion of the streams, the bulbous portions 79 of each ofthe streams contact and bond with the streams which are adjacentthereto, after which the extruded material is set, as by streams of coolair. The resulting product exhibits a cellular structure throughout andis generally similar to that shown in FIG. 4 of the drawing.

The articles produced by the method shown in FIGS. 6 and 7 areessentially the same as that shown in FIGS. 2 and 4, with the exceptionthat the elongated members forming the same are of cellular or foamedstructure through their lengths. Such articles may be stretched tomolecularly orient the same. Further, as with the method shown in FIGS.1 and 4, the methods illustrated in FIGS. 6 and 7 may be used in makingmultilayered articles similar to those shown in FIGS. 3 and 5,respectively.

As heretofore mentioned, the articles of the present invention areadapted for a variety of uses. One such use is illustrated in FIG. 8wherein a cellular article, as produced by the method of FIG. 6, isbonded to and between a pair of cover sheets 81 to provide a compositeproduct 83 having good heat-, sound, and shock-insulating properties.

It is to be understood that changes and variations may be made withoutdeparting from the spirit and scope of the invention as defined in theappended claims.

lclaim:

1. An article of manufacture including a plurality of generallyparallel, elongated members, at least some of said members havingbulbous portions at spaced intervals along the lengths thereof which arebonded to members which are adjacent thereto whereby the plurality ofelongated members together provide an integral article, said elongatedmembers being formed of a polymeric material the molecules of which areoriented at least along one of the longitudinal and transversedirections of the article.

2. An article as defined in claim 1 wherein the bulbous portions of saidmembers are aligned generally transversely of a plane extendinglongitudinally of such members and are bonded to each other.

3. An article as defined in claim I wherein the bulbous portions of saidmembers are located between the bulbous portions of the members adjacentthereto.

4. An article as defined in claim 1 in which the elongated members areformed ofa foamed polymeric material.

2. An article as defined in claim 1 wherein the bulbous portions of saidmembers are aligned generally transversely of a plane extendinglongitudinally of such members and are bonded to each other.
 3. Anarticle as defined in claim 1 wherein the bulbous portions of saidmembers are located between the bulbous portions of the members adjacentthereto.
 4. An article as defined in claim 1 in which the elongatedmembers are formed of a foamed polymeric material.